Some structural and functional characteristics of a soil nematode community from a Mediterranean grassland

This paper refers to the effects of large-scale seasonal fluctuations as well as experimentally induced small-scale variations of soil temperature and moisture on the structural and functional characteristics of a soil nematode community from a Greek Mediterranean grassland. Two levels of soil temperature, with a mean difference of 1.4 degrees C, and two levels of moisture (2.3 \% difference in water content) were created. The experiment lasted for a six-month period (from July to December). All nematode community parameters vary significantly with season, with the exception of the environmental constant (C(env)), which reflects the intensity of competition. The Maturity Index (MI) is affected only by seasonally fluctuating soil conditions, while the Plant Parasite Index (PPI) is affected only by the small-scale differences in soil temperature and moisture. The high value (1.48) of bacterivorous to fungivorous ratio (B/F) indicates mainly bacterial mediated decomposition, resulting in good soil fertility. The B/F ratio is affected both by large and small-scale changes in soil conditions. Diversity and richness show dependence on seasonal variations as well as on small changes in temperature, while no effect of moisture is recorded. The correlations between nematode community parameters, microflora parameters and soil nitrogen pools show independence of nematode parameters from soil N-pools (N(organic) and N(inorganic)) and parameters relating to microflora, as well as strong dependence on microbially-bounded nitrogen.